Asphalt pavement using an asphalt mixture has been frequently employed for paving driveways, parking spaces, cargo yards, sidewalks, etc., because of relatively easy construction and a short period of time from beginning of paving works to traffic opening. For example, in current driveways in Japan, 95% of a whole paved road surface thereof have been constructed from the asphalt pavement.
The asphalt pavement includes a road surface which is formed of an asphalt mixture containing aggregates bonded with each other through asphalt, and exhibits a good hardness and a good durability.
However, asphalt produced by refining of petroleum is apt to be dissolved in similar petroleum refined products such as gasoline, light oils, heavy oils and engine lubricants. For this reason, if these oils are dropped on the road surface owing to leakage of fuels or lubricants from vehicles, etc., the asphalt tends to be dissolved in the oils at an early stage after being paved, which will lead to erosion of the asphalt mixture and occurrence of pavement fracture such as formation of pot holes. Therefore, in such a case, repair of the pavement is inevitably needed, which results in increased maintenance costs and significant influence on car traffic.
To take measures against these problems, cement concrete pavements have been used because they are excellent in oil resistance and durability as compared to the asphalt pavements. However, in the cement concrete pavements, a laying speed thereof tends to be low owing to need of a prolonged time upon curing of the cement, and removal of concrete plates is required upon repair. Thus, the cement concrete pavements are hardly adoptable in practice because it is very difficult to avoid a large adverse influence on traffic.
On the other hand, as the paving method using an asphalt-based mixture having a high laying speed, there is considered a paving method using a semi-flexible asphalt mixture for pavements which has a relatively high oil resistance. The pavement using the semi-flexible asphalt mixture is constructed by curing a cement milk filled into voids of an open-graded asphalt mixture, and therefore exhibits a high rutting resistance and an excellent durability owing to the cured cement. The semi-flexible asphalt mixture has a good oil resistance as compared to ordinary asphalt mixtures, but needs such a complicated procedure that after laying the open-graded asphalt mixture as a mother material, the cement milk is injected into the voids of the asphalt mixture. As a result, similarly to the cement concrete pavements, there tend to occur such a problem that a laying time for constructing the pavement using the semi-flexible asphalt mixture is two or more times the laying time when using ordinary asphalt mixtures.
In addition, there is also known a paving method using another type of an asphalt-based mixture in which an epoxy asphalt mixture containing an epoxy resin having a relatively high oil resistance is used. The epoxy asphalt mixture is such an asphalt mixture prepared by replacing about 15 to 30% of asphalt in the ordinary asphalt mixture with an epoxy resin. The epoxy resin used in the epoxy asphalt mixture is in the form of a reactive resin constituted from two liquids including a main resin component and a curing agent. The cured product of the epoxy resin is undissolved in oils and therefore exhibits a relatively high oil resistance, and a pavement obtained by using the epoxy asphalt mixture has a high rutting resistance and an excellent durability owing to the cured epoxy resin.
However, the epoxy asphalt mixture is cured by reaction of the epoxy resin, so that a laying workability thereof is largely influenced by a temperature used for mixing respective components thereof. If the mixing temperature is excessively high, the resulting epoxy asphalt mixture tends to be cured too fast, thereby failing to suitably lay the mixture on a road surface. When the mixing temperature is excessively low, the epoxy asphalt mixture tends to be cured too slowly, thereby causing problems such as a prolonged time until traffic opening and occurrence of early rutting after the traffic opening. Further, the use of the epoxy asphalt mixture of a two-liquid type needs a special apparatus for addition of the epoxy resin.
As an alternative measure, it is considered to use a modified asphalt prepared by compounding a thermoplastic elastomer such as typically SBS (styrene-butadiene-styrene block copolymer) in asphalt. In fact, the modified asphalt has an effect of enhancing a resistance to rutting and cracking which will be caused in asphalt pavements. In recent years, the modified asphalt has been put into practice in many cases. The modified asphalt is considered to exhibit a higher oil resistance than straight asphalts owing to a high viscosity thereof. However, since many of the thermoplastic elastomers used in the modified asphalt are in the form of a petroleum product, the modified asphalt is apt to be dissolved in petroleum-based oils, resulting in inevitable occurrence of pavement fracture such as formation of pot holes.
Thus, the conventionally known methods have failed to solve the above-described problems.
On the other hand, various methods for enhancing properties of the asphalt pavement have been proposed.
For example, JP 3-17304β discloses the method in which a planar material having a net-work structure which is produced by coating a fiber bundle of aromatic polyamide fibers having a fiber diameter of 12 μm with a vinyl chloride resin is used as a reinforcing material for an asphalt mixed material, and disposed in a grid-like manner in the asphalt mixed material to enhance a rutting resistance of the asphalt mixed material.
However, it is usually difficult to increase an amount of the polyamide compounded in such a fibrous material, i.e., the amount of the polyamide compound therein is limited to about several % on the basis of the asphalt in view of a good workability of the resulting material. In addition, even when the asphalt compounded with the fibrous polyamide is subjected to heat-mixing and compaction upon forming a pavement, it will be difficult to uniformly disperse the polyamide fibers over the pavement. As a result, when oils are leaked on the paved surface, the pavement tends to hardly exhibit a good oil resistance. Further, in the paving method described in JP 3-17304A, after laying the net-work structure composed integrally of the fibers and the thermoplastic resin on a road surface, the asphalt mixed material is applied on the net-work structure. Therefore, the paving method requires a number of steps for laying these materials, resulting in problems such as a prolonged laying time.
Under these circumstances, it has been required to provide an asphalt mixture which is relatively readily laid over a road surface and has advantages such as a high laying speed and a short period of time from beginning of paving work to traffic opening, and which is further capable of realizing construction of a pavement having an excellent oil resistance and a high durability.
On the other hand, there is such a proposal that an amide compound is used for asphalt pavement.
U.S. Pat. No. 6,786,963 discloses a paving composition containing an amide compound such as a diamide compound as an anti-stripping agent.